EP3264981B1 - Assistance device intended for a person suffering motor disorders of neurological origin - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION AND BACKGROUND

The present invention relates to a mobility assistance device intended for people suffering from motor disorders of neurological origin, in particular those due to a neurodegenerative disease such as Parkinson's disease. By the terms “motor disorders” is meant a loss of control by the user, partial or total, of the muscles allowing him to move. These motor disorders are likely to prevent this person from walking or cause them to fall. More specifically, the present application relates to an assistance device making it possible to trigger an auditory stimulation of the user wearing said device, when an episode of motor disorders is likely to occur or does occur, in order to allow it to prevent the occurrence. of it.

By the term "neurological origin" is meant the fact that the motor disorders are caused by an alteration, in the affected person, of the nervous system, rather than by osteo-articular or muscular disorders. Neurodegenerative diseases are generally the cause of this alteration, and the invention is aimed particularly at people who are affected by them, and in particular among these idiopathic Parkinson's disease, parkinsonian syndromes, multisystem atrophy, Lewy body dementia, or progressive supranuclear palsy, among others. Other diseases such as multiple sclerosis may be concerned, as well as accidental alterations such as the consequences of a stroke or a transient ischemic attack. The following description will be made with reference to idiopathic Parkinson's disease as a non-limiting illustrative example.

Idiopathic Parkinson's disease is the second neurodegenerative disease after Alzheimer's disease. The age of entry into the disease is between 58 and 62 years and more rarely (in less than 10% of cases) before 40 years. This pathology is characterized by an alteration in the functioning of the basal ganglia system (putamen, globus pallidus, locus niger and the subthalamic nucleus). Basal ganglia are subcortical nuclei in the brain that are part of a motor circuit (including the thalamus, motor cortex, and prefrontal cortex) responsible primarily for controlling voluntary movement. In idiopathic Parkinson's disease, there is a depopulation of dopaminergic neurons from the niger locus which are related to the striatum (impairment of nigro-striated bundles). The nigrostriotic involvement causes a decrease in the activation of the thalamus which leads to difficulties in initiating voluntary movements. For many years, Parkinson's disease was considered solely as a pathology of motor skills characterized by the "parkinsonian triad". This includes three symptoms which are resting tremor, muscle stiffness and akinesia. At the onset of Parkinson's disease, the symptoms are classically unilateral and then become bilateral, always remaining asymmetric.

The parkinsonian triad causes motor disorders which, associated with postural instability, generate walking disorders and often traumatic falls (fractures of the neck of the femur, cranial traumas). The lack of dopamine at the nigrostriotic level would partly explain these motor disorders. The normal elderly subject shows a deterioration of gait, a decrease in the speed of gait, the length of the steps, an increase in the frequency of the steps and an asymmetry and variability of the steps. In the subject with parkinsonian syndrome, these deficits are much more marked. Among the walking disorders, we also find the kinetic clutch (or "Freezing" for "Freezing of Gait" in English). This is a disorder of the march defined as a reduction of progression despite not intent about wanting to move, which leads generally a total shutdown patient with Parkinson's disease, despite the intention to want to move forward . Kinetic clutch is present in the vast majority of patients at an advanced stage.

The kinetic clutch is manifested during the initiation of walking (especially after getting up from the chair or bed or after a prolonged immobilization) or during this one favored by the situation of double task including mental arithmetic, by the stress, narrow passages, as well as doorways. Kinetic clutch, or “freezing”, is characterized by an increase in the frequency of walking, associated with a reduction in the length of the strides, but also by the sensation of the feet “magnetized to the ground”. This phenomenon of kinetic clutch is one of the most debilitating symptoms of Parkinson's disease, significantly altering the quality of life of patients.

The phenomenon of kinetic clutch can be mitigated or avoided by making a patient listen to a rhythmic pulse. More precisely, it consists of the presentation of rhythmic auditory cues (for example the sounds of a metronome or of music), in order to help the patient to walk better by allowing him to regularize, stabilize his movements, thanks to the synchronization of the movements of its members with music for example.

The document US 2010/0274304 A1 describes an example of a type of device, placed on a shoe of the user and emitting a signal when the device detects an irregularity in the pace of steps. More precisely, the signal is emitted from the moment when the user is no longer moving forward. The transmitted signal is then transformed into an auditory signal by a receiver-transmitter placed at the level of the user's ear, to enable him to re-engage his walk. In other words, this device allows the user to reset his walk after it was interrupted by a phenomenon of kinetic clutch. However, such detection is imperfect, since the change in walker pace can be caused by various factors other than kinetic engagement. The result is an untimely triggering of the auditory stimulation, which is annoying and dissuades the person from using the device.

The document US 2012/101411 A1 a method of collecting data relating to the kinetic clutch, which comprises collecting movement data, determining from these data a movement parameter including a third order derivative of the position, comparing the parameter of movement with a threshold value, and count at least one near drop if the movement parameter exceeds a threshold value. This approach does not distinguish between the postures nor does it take into account a threshold crossing time, which implies the choice of an insensitive threshold, preventing early detection of kinetic engagement.

The document US 2009/204030 A1 deals with a method of rehabilitation of patients with motor disabilities, and in particular hemiplegic patients. The essential idea is to evaluate the functional use of a limb by determining the synchronicity of the patient's movements as a function of the cyclicity of the movement. Such an approach does not allow early and reliable detection of kinetic engagement.

The document WO 2009/083032 A1 describes a method for detecting episodes of physical blocking of an individual's activity. This method includes acquiring a motion signal from at least one body part of the individual. The movement signals can be static or dynamic accelerations, and speeds of rotation of that part of the body. The jerk is then calculated from static or dynamic accelerations. The movement is considered stable or not depending on whether the jerk remains or not below a threshold. This approach does not distinguish between the postures nor does it take into account a threshold crossing time, which implies the choice of an insensitive threshold, preventing early detection of kinetic engagement.

There is a need for a motor assistance device making it possible to prevent the occurrence of a phenomenon of kinetic engagement of the gait of a user wearing said device and allowing early detection of a phenomenon of kinetic engagement of the movement. the walking of a user wearing said device, in order to allow him to regain normal walking, while avoiding untimely triggering of the device in the absence of kinetic clutch.

PRESENTATION OF THE INVENTION

The object of the invention is to remedy at least in part these drawbacks and preferentially to all, by proposing a device for assisting motor skills intended for a person suffering from motor disorders of neurological origin so that it makes it possible to avoid the occurrence of a kinetic clutch, and in the case of a kinetic clutch, to detect its occurrence as quickly as possible, without false-positive, and which makes it possible to auditally stimulate this person so that they regain acceptable motor skills.

• un accéléromètre adapté pour être porté par la personne pour mesurer des accélérations selon au moins une première direction qui correspond à l'axe horizontal ; et
• des moyens de mémorisation mémorisant une pluralité de valeurs seuils d'accélération de prévention préalablement définies pour ladite première direction ; et
• des moyens d'émission d'une stimulation auditive perceptible par la personne portant l'accéléromètre; et
• des moyens de calcul connectés à l'accéléromètre, aux moyens de mémorisation et aux moyens d'émission ;

le dispositif d'assistance comprenant des moyens de mémorisation mémorisant une pluralité de valeurs seuils d'accélération d'anticipation préalablement définies pour ladite première direction, chaque valeur seuil d'accélération d'anticipation étant associée à une posture , et les moyens de calcul étant configurés pour :

1. a) déterminer une posture de la personne à partir des accélérations mesurées,
2. b) comparer les accélérations mesurées par la centrale inertielle dans la première direction par rapport à au moins une valeur seuil d'accélération d'anticipation associée à ladite posture ;
3. c) commander l'émission d'une stimulation auditive en fonction du franchissement de ladite valeur seuil d'accélération d'anticipation associée à ladite posture;

le dispositif d'assistance étant caractérisé en ce que les moyens de calcul sont configurés pour :

• associer également chaque posture à une durée déterminée fonction du sens de franchissement de ladite valeur seuil d'accélération d'anticipation par les accélérations mesurées, et
• commander l'émission de la stimulation auditive en fonction du franchissement de ladite valeur seuil d'accélération d'anticipation associée à ladite posture pendant la durée déterminée.

There is thus proposed an assistance device intended for a person suffering from motor disorders of neurological origin, comprising:

• an accelerometer adapted to be worn by the person to measure accelerations in at least a first direction which corresponds to the horizontal axis; and
• storage means memorizing a plurality of prevention acceleration threshold values previously defined for said first direction; and
• means for transmitting an auditory stimulation perceptible by the person wearing the accelerometer; and
• calculation means connected to the accelerometer, to the storage means and to the transmission means;

the assistance device comprising storage means storing a plurality of anticipation acceleration threshold values defined beforehand for said first direction, each anticipation acceleration threshold value being associated with a posture, and the calculation means being configured for:

1. a) determine a posture of the person from the measured accelerations,
2. b) comparing the accelerations measured by the inertial unit in the first direction with respect to at least one anticipatory acceleration threshold value associated with said posture;
3. c) controlling the emission of an auditory stimulation as a function of the crossing of said anticipation acceleration threshold value associated with said posture;

the assistance device being characterized in that the calculation means are configured for:

• also associate each posture with a determined duration depending on the direction of crossing of said anticipatory acceleration threshold value by the measured accelerations, and
• controlling the emission of the auditory stimulation as a function of the crossing of said anticipation acceleration threshold value associated with said posture during the determined period.

• les postures comprennent la posture assis-couché, et une valeur seuil d'accélération d'anticipation associée à la posture assis-couché correspond à un déséquilibre vers l'arrière ;
• les postures comprennent la posture debout, une valeur seuil d'accélération d'anticipation associée à la posture debout correspondant à un déséquilibre vers l'arrière et une valeur seuil d'accélération d'anticipation associée à la posture debout correspondant à un déplacement vers l'avant ;
• le dispositif comprend une centrale inertielle de laquelle fait partie l'accéléromètre, ladite centrale inertielle étant en outre configurée pour déterminer une orientation du tronc de la personne, ladite orientation étant utilisée pour déterminer la posture de la personne;
• l'accéléromètre est également adaptée pour mesurer des accélérations selon une seconde direction, ladite seconde direction correspondant à la verticale, et les moyens de mémorisation mémorisent au moins une valeur seuil d'accélération d'alerte préalablement définie dans une seconde direction, les moyens de calculs étant en outre configurés pour :
  1. a) comparer les accélérations mesurées par la centrale inertielle dans la seconde direction,
  2. b) générer un signal d'alerte lorsqu'une accélération mesurée a une valeur supérieure à la valeur seuil d'accélération d'alerte,
  3. c) commander aux moyens d'émission d'émettre une stimulation auditive en fonction du signal d'alerte ;
• les moyens de mémorisation mémorisent une valeur seuil de temps et une valeur seuil d'accélération de marche, et les moyens de calculs sont configurés pour mesurer un intervalle de temps entre deux mesures d'accélérations dépassant ladite valeur seuil d'accélération de marche et déclencher une alerte lorsqu'un intervalle de temps entre deux dépassements consécutifs de ladite valeur seuil d'accélération de marche est inférieur à la valeur seuil de temps mémorisée ;
• les moyens de mémorisation mémorisent une période de référence correspondant à la valeur seuil de temps, et en ce que les moyens de calcul commandent aux moyens d'émission d'émettre la stimulation auditive selon la période de référence ;
• les moyens de calcul sont configurés pour commander aux moyens d'émission d'émettre une stimulation auditive à partir du moment où au moins deux signaux d'alerte sont générés dans un intervalle de temps inférieur à 0,5 seconde, de préférence inférieur à 0,3 seconde ;
• le dispositif comprend :
  • des moyens de mesure du rythme cardiaque adaptés à être portés par la personne pour mesurer son rythme cardiaque ; et
  • les moyens de mémorisation mémorisent une valeur seuil de rythme cardiaque ; et les moyens de calculs sont configurés pour générer un signal d'alerte lorsque le rythme cardiaque mesuré a une valeur supérieure à la valeur seuil de rythme cardiaque mémorisée ;
• l'accéléromètre est configuré pour mesurer une accélération selon une autre direction différente de celle de la seconde direction, et les moyens de mémorisation mémorisent une seconde valeur seuil d'accélération, et les moyens de calculs sont configurés pour inhiber la génération d'un signal d'alerte pendant une durée prédéterminée lorsqu'une accélération mesurée dans l'autre direction a une valeur supérieure à la seconde valeur seuil d'accélération mémorisée ;
• les moyens de calcul sont configurés pour déterminer à partir des mesures d'accélération mesurées par l'accéléromètre, l'orientation du tronc de la personne ;
• les moyens de mémorisation mémorisent une valeur seuil d'accélération marche et une valeur de temps repos, et les moyens de calcul détectent une position assise ou couchée de la personne portant l'accéléromètre lorsque toutes les valeurs d'accélération mesurées par l'accéléromètre sont inférieures à la valeur seuil d'accélération marche pendant une durée supérieure à la valeur de temps repos ;
• les moyens de calcul sont configurés pour comparer les accélérations mesurées par les accéléromètres de façon périodique, la valeur de cette période étant égale à :
• une première période de mesure lorsque le tronc de la personne est horizontal ; et/ou
• une deuxième période de mesure inférieure à la première valeur, lorsque le tronc de la personne est vertical ; et
• une troisième période de mesure inférieure à la deuxième valeur, lorsque la personne marche.

This device is advantageously supplemented by the following characteristics, taken alone or in any of their technically possible combinations:

• the postures include the sit-lying posture, and an anticipatory acceleration threshold value associated with the sit-lying posture corresponds to a backward imbalance;
• the postures include the standing posture, an anticipatory acceleration threshold value associated with the standing posture corresponding to a backward imbalance and a threshold anticipation acceleration value associated with the standing posture corresponding to a displacement towards the back 'before ;
• the device comprises an inertial unit of which the accelerometer forms part, said inertial unit being further configured to determine an orientation of the trunk of the person, said orientation being used to determine the posture of the person;
• the accelerometer is also suitable for measuring accelerations in a second direction, said second direction corresponding to the vertical, and the storage means memorize at least one warning acceleration threshold value defined beforehand in a second direction, the means of calculations being further configured for:
  1. a) compare the accelerations measured by the inertial unit in the second direction,
  2. b) generate an alert signal when a measured acceleration has a value greater than the alert acceleration threshold value,
  3. c) commanding the transmission means to emit an auditory stimulation as a function of the alert signal;
• the storage means memorize a time threshold value and a walking acceleration threshold value, and the calculation means are configured to measure a time interval between two acceleration measurements exceeding said walking acceleration threshold value and trigger an alert when an interval of time between two consecutive exceedances of said walking acceleration threshold value is less than the stored time threshold value;
• the storage means memorize a reference period corresponding to the time threshold value, and in that the calculation means command the transmission means to emit the auditory stimulation according to the reference period;
• the calculation means are configured to command the transmission means to emit an auditory stimulation from the moment when at least two alert signals are generated in a time interval of less than 0.5 seconds, preferably less than 0 , 3 second;
• the device includes:
  • means for measuring the heart rate adapted to be worn by the person to measure his heart rate; and
  • the storage means memorize a heart rate threshold value; and the calculation means are configured to generate an alert signal when the measured heart rate has a value greater than the stored heart rate threshold value;
• the accelerometer is configured to measure an acceleration in another direction different from that of the second direction, and the storage means memorize a second threshold acceleration value, and the calculation means are configured to inhibit the generation of a signal alerting for a predetermined time when an acceleration measured in the other direction has a value greater than the second stored acceleration threshold value;
• the calculation means are configured to determine from the acceleration measurements measured by the accelerometer, the orientation of the trunk of the person;
• the storage means memorize a threshold value of acceleration on and a value of rest time, and the calculation means detect a sitting or lying position of the person wearing the accelerometer when all the acceleration values measured by the accelerometer are less than the threshold value of acceleration on for a period greater than the value of rest time;
• the calculation means are configured to compare the accelerations measured by the accelerometers periodically, the value of this period being equal to:
• a first measurement period when the trunk of the person is horizontal; and or
• a second measurement period less than the first value, when the trunk of the person is vertical; and
• a third measurement period less than the second value, when the person is walking.

• l'accéléromètre est disposé sur la personne,
• une série de mesures d'accélération est acquise pendant que la personne marche,
• la série est amputée des parties de la série de mesures d'accélération correspondant à une motricité altérée de la personne,
• les valeurs d'accélération d'anticipation et/ou une valeur seuil d'accélération d'alerte est déterminée à partir de la moyenne des accélérations de la série amputée.

The invention also relates to a method for calibrating an assistance device according to one of the preceding claims, comprising the steps according to which:

• the accelerometer is placed on the person,
• a series of acceleration measurements is acquired while the person is walking,
• the series is cut off from the parts of the series of acceleration measurements corresponding to impaired motor skills of the person,
• the anticipation acceleration values and / or an alert acceleration threshold value is determined from the average of the accelerations of the amputated series.

Preferably, the walking acceleration threshold value and / or the time threshold value is determined from the average of the accelerations of the amputated series.

PRESENTATION OF FIGURES

• la figure 1 est un schéma illustrant une personne atteinte de troubles moteurs d'origine neurologique utilisant un dispositif d'assistance selon un mode de réalisation possible de l'invention ;
• la figure 2 est un schéma illustrant les accélérations selon la direction verticale mesurées par un accéléromètre montrant un enrayage cinétique.

The invention will be better understood, thanks to the description below, which relates to embodiments and variants according to the present invention, given by way of non-limiting examples and explained with reference to the accompanying schematic drawings, in which :

• the figure 1 is a diagram illustrating a person suffering from motor disorders of neurological origin using an assistance device according to a possible embodiment of the invention;
• the figure 2 is a diagram illustrating the accelerations in the vertical direction measured by an accelerometer showing a kinetic engagement.

DETAILED DESCRIPTION

In the present description, the term vertical is understood to mean a direction parallel to the direction of gravity or perpendicular to the plane of the horizon. By horizontal is meant a direction perpendicular to the vertical, therefore perpendicular to the direction of gravity.

By posture is meant the position of the body at a given moment, as opposed to a movement. A posture is for example the standing position or the sitting position.

With reference to the figure 1 , an assistance device comprises a housing 3 in which is housed an accelerometer adapted to be worn by the person 1 to measure accelerations in at least one direction. Preferably, the accelerometer is adapted to be worn on the trunk 2 of the person. By trunk is meant the part of the human body extending from the pelvis to the shoulders. The accelerometer is for example a piezoelectric accelerometer comprising a polysilicon surface structure suspended above a silicon wafer by a silicon spring having resistance against the acceleration forces. The deformation of the structure is measured by means of a differential capacitance.

The accelerometer may be part of an inertial unit, comprising, in addition to an accelerometer capable of measuring accelerations in one or more directions, one or more gyros capable of measuring angular speeds and / or one or more gyroscopes capable of measuring positions angular. Thus, preferably, the device comprises an inertial unit of which the accelerometer forms part, said inertial unit being configured to determine an orientation of the trunk of the person. As indicated for the accelerometer, the inertial unit is preferably adapted to be worn on the trunk of the person.

The accelerometer is preferably adapted to be worn at waist level. So on the figure 1 , the person suffering from Parkinson's disease wears around the waist a belt 4 provided with the housing 3 comprising this first accelerometer. Preferably, the accelerometer is suitable for measuring accelerations in at least a second direction, different from the first direction, and preferably orthogonal to the first direction. Typically, the accelerometer is capable of determining acceleration measurements in three directions orthogonal to each other, and therefore of reconstructing the acceleration in any direction, as well as the orientation of the accelerometer, and therefore of the trunk 2 of person 1.

Thus, whether it is directly measured or reconstructed, the first direction corresponds to the horizontal direction with respect to the person wearing the device. More precisely, the first direction is essentially horizontal, that is to say that the horizontal component of the first direction is preponderant over the vertical direction.

The motion sensor comprising the accelerometer is adapted to be positioned on the user. The accelerometer can in particular be positioned at the level of the trunk, hips, plexus, or lower limbs of the user. Preferably, the motion sensor is positioned so as to be able to measure the accelerations at the hip, bust or plexus level. The motion sensor is thus positioned at one of these parts of the body. Indeed, the measurement of the accelerations in these places makes it possible to take into account the movements of the whole of the two legs, which does not allow an accelerometer placed on one foot, while above the torso, for example on the shoulders , the damping by the body is too great. Thus, more preferably, the movement sensor is positioned at the level of the iliac crest of the person 1.

The box 3 also comprises calculation means, for example a processor or a computer, a microcontroller, a calculation unit, or an arithmetic and logic unit, and storage means. The calculation means are connected to the accelerometer, for example by a wireless link or by waves or by a wired link, and to the storage means, for example by a physical link. The calculation means and the storage means are typically arranged on the same electronic card, or on several separate cards and connected to one another.

The storage means memorize at least a plurality of prevention acceleration threshold values previously defined for the horizontal direction. These prevention acceleration threshold values are associated with postures of the person, and determined durations are associated with each anticipation acceleration threshold value. More precisely, a determined duration associated with an anticipation acceleration threshold value depends on the direction in which said anticipation acceleration threshold value is crossed. Thus, for each anticipation acceleration threshold value, there is a determined duration for crossing from accelerations below said threshold value to accelerations above said threshold value, and a determined duration for crossing from higher accelerations. at said threshold value towards accelerations below said threshold value, and these two determined durations are different for at least most of the threshold values.

However, in order to implement different functionalities of the device, the storage means can also memorize other values, and in particular among them at least one alert acceleration threshold value, a time threshold value, a threshold value d. gait acceleration, and / or a heart rate threshold value.

The device also contains means for transmitting an auditory stimulation perceptible by the person wearing the accelerometer. The emission means comprise a transducer 5 adapted to emit sounds, which may take the form of an atrium to be placed in the ear canal of the wearer of the device, or else a transducer adapted to be placed against a temporal bone of the wearer in order to to stimulate said bone, such as for example a device implementing osteophony. The transmission means are connected to the box 3, and more precisely to the calculation means, by a link 6, which can be wired as on the figure 1 , or be wireless or by waves.

The device may also include a heart rate monitor, adapted to measure the heart rate of the person wearing the device. This can be worn when using the device for assistance with motor skills, or else only when calibrating it. The device also comprises at least one battery supplying the various components of the device with electrical energy.

1. a) déterminer une posture de la personne à partir des accélérations mesurées,
2. b) comparer les accélérations mesurées par ledit accéléromètre dans la première direction par rapport à au moins une valeur seuil d'accélération d'anticipation associée à ladite posture ;
3. c) commander l'émission d'une stimulation auditive en fonction du franchissement de ladite valeur seuil d'accélération d'anticipation associée à ladite posture pendant une durée déterminée associée à ladite valeur seuil d'accélération d'anticipation.

In the assistance device, the calculation means are configured for:

1. a) determine a posture of the person from the measured accelerations,
2. b) comparing the accelerations measured by said accelerometer in the first direction with respect to at least one anticipatory acceleration threshold value associated with said posture;
3. c) controlling the emission of an auditory stimulation as a function of the crossing of said anticipation acceleration threshold value associated with said posture for a determined duration associated with said anticipation acceleration threshold value.

The device is thus configured to stimulate the wearer of said device when he is in motion during phases of probability of occurrence of a phenomenon of kinetic engagement of walking, these phases being determined by the comparison between the measured accelerations and values. anticipation acceleration threshold. More precisely, it is a question of comparing the amplitudes of these accelerations with anticipatory acceleration threshold values.

The likelihood of this happening also depends on the user's posture. Thus, each anticipation acceleration threshold value is associated with a posture. Several acceleration threshold values can be associated with the same posture. The direction taken into account here is that of the horizontal, and the direction of the accelerations is that of the forward displacement of the user.

In order not to unnecessarily stimulate the user, the emission of the stimulation is conditioned on the crossing of an anticipation acceleration threshold value for a determined duration associated with it. Typically, the determined duration during which the acceleration must exceed the threshold is between 150 ms and 2.5 seconds. The determined time during which the acceleration must exceed the threshold depends on the anticipation acceleration threshold value, which itself depends on the posture. Therefore, the determined duration also depends on the posture. The postures can include the sit-down posture and the standing posture. For example, if the user's posture is determined to be sitting or lying down, the predetermined time may be between 200 msec and 1 second. If the user's posture is determined to be standing, the predetermined time can be between 150 ms and 2.5 seconds. This determined duration may depend on the direction of crossing, as explained above.

The posture of the person can be determined from the measured accelerations. In addition, or as an alternative, it can also be determined from the orientation of the user's trunk that an inertial unit, carried on this trunk, can determine.

The measurement of the accelerations makes it possible to determine the orientation of the device. One can for example determine gravity or integrate accelerations. Depending on the orientation of the device, it is possible to determine the position of the person, and therefore his posture in combination with the accelerations. We can therefore determine the posture of the person by accelerations. For example, it can be determined that the person is sitting or lying down if the device is tilted backwards, with a tilt threshold being exceeded for a certain duration (several seconds). Likewise, it is also possible to determine that the person is standing if the position of the device is parallel or perpendicular to the ground (depending on the configurations), in a stable manner (over several seconds).

The postures can include the sit-down posture and the standing posture. In the case of the sit-lying posture, an anticipatory acceleration threshold value associated with the sit-lying posture corresponds to a backward imbalance, the auditory stimulation being emitted when the measured accelerations are greater than said threshold value anticipation acceleration associated with the sit-lying posture corresponding to a backward imbalance. For example, the anticipatory acceleration threshold value associated with the sit-lying posture corresponding to a backward imbalance is between - 1.2 ms- ² and -1.7 ms- ² , for example -1 , 5 ms- ² , and the predetermined duration associated with it is between 0.5 and 1 second.

For example, if the user's posture is determined to be sitting or lying down, stimulation is output when accelerations greater than -1.5 ms ^-2 in the horizontal direction are measured for at least 0.5 s . Otherwise, no stimulation is emitted.

In the case of the standing posture, an anticipatory acceleration threshold value associated with the standing posture corresponding to an imbalance towards the rear and a threshold anticipation acceleration value associated with the standing posture corresponding to a displacement towards the front. The auditory stimulation is emitted when the measured accelerations are less than the threshold value of anticipation acceleration associated with the standing posture corresponding to a backward imbalance and when the measured accelerations are greater than the threshold value of acceleration of anticipation associated with the standing posture corresponding to a forward movement.

For example, the anticipatory acceleration threshold value associated with the standing posture corresponding to a backward imbalance is between -0.8 ms- ² and -1.2 ms- ² , for example -1 ms- ² , and the predetermined duration associated with it is between 150 and 250 ms, for example 200 ms, and the anticipation acceleration threshold value associated with the standing posture corresponding to a forward movement is between 2, 5 and 3 ^ms-2 , for example 2.8 ms- ² , and the predetermined duration associated with it is between 150 and 250 ms, for example 200 ms.

For example, if the user's posture is determined to be standing, stimulation is emitted when accelerations greater than 2.8 ms ^-2 for 0.2 s or between -1.5 ms ^{-2 are measured.} and -1 ms ^-2 for 0.2 s. Otherwise, no stimulation is emitted.

Table 1 below gives an example of the thresholds used, depending on the posture determined by the device. Posture Accelerations on the horizontal axis (in ms ^-2 ) -infinity -1.5 -1 2.8 + infinity Sitting-lying No stimulation stimulation No stimulation No stimulation Standing No stimulation stimulation No stimulation stimulation

Table 2 below gives examples of predetermined duration which can be associated with the threshold values of accelerations given in Table 1, as a function of the direction of crossing, for different postures determined by the device. Posture Accelerations Positive direction crossing Negative direction crossing Sitting-lying -1.5 350 ms 500 ms Standing -1 2500 ms 200 ms 2.8 Between 200 and 500 ms Between 350 and 2500 ms

We call here "crossing in the positive direction" a crossing of the threshold from accelerations below said threshold value towards accelerations above said threshold value, and "crossing in the negative direction" means crossing from accelerations above said threshold value towards accelerations below said threshold value. said threshold value.

When the stimulation conditions are met, the calculation means command the transmission means to emit the auditory stimulation according to a reference period corresponding to a calculated frequency of the person's steps. The auditory stimulation comprises a rhythmic pulse, which can be isolated and correspond, for example, to a repetition of a short sound, or even be coupled with other sounds, as in the case of a melody. In all cases, the rhythmic pulse is easily identifiable by the user. The period of the pulse of the auditory stimulation is based on a reference period stored in the storage means. The period of the pulsation is calculated based on the average period of steps when the person walks without exhibiting kinetic clutch. It therefore varies depending on the individual. For example, when the person walks with an average of 140 steps per minute, this amounts to a period of about 0.43 seconds between each step. The period of the pulse of the auditory stimulation is then 0.43 seconds.

The auditory stimulation can be emitted, as the case may be, as long as the conditions for its emission are met, be continued for a certain time even after these conditions have ceased to be met and / or stop after a certain time. fixed term even when the conditions are met. For example, as part of the back imbalance, the auditory stimulation can be emitted as long as the measured accelerations are between -1.5 ms ^-2 and -1 ms ^-2 . In this case of forward movement, the stimulation can be continued for 40 to 50 seconds when the corresponding acceleration threshold is crossed (for example the threshold of 2.8 ms ^-2 .

Preferably, the storage means memorize at least one warning acceleration threshold value, and the accelerometer is also suitable for measuring accelerations in a second direction, said second direction corresponding to the vertical.

1. a) comparer les accélérations mesurées dans la seconde direction par rapport à la valeur seuil d'accélération d'alerte ;
2. b) générer un signal d'alerte lorsqu'une accélération mesurée a une valeur supérieure à la valeur seuil d'accélération d'alerte.

In the assistance device, the calculation means are then further configured to perform the following steps:

1. a) comparing the accelerations measured in the second direction with respect to the alert acceleration threshold value;
2. b) generating an alert signal when a measured acceleration has a value greater than the alert acceleration threshold value.

Indeed, at the beginning of a kinetic clutch, the person suffering from Parkinson's disease presents a disharmonious and asymmetric walk from the anatomofunctional point of view. The steps become narrower, closer, and faster. This results, in terms of measured vertical acceleration, by greater acceleration amplitudes, which will consequently exceed a warning acceleration threshold value, and therefore trigger the generation of a warning signal. The alert acceleration threshold value is set according to each person, but is typically included, in absolute value, between 1 and 7 ms ^-2 , more precisely between 2 and 6 ms ^-2 , and even more precisely between 3 and 5 ms ^-2 . The occurrence of a kinetic clutch episode can thus be detected as quickly as possible. Then, the calculation means are configured to command the transmission means to emit an auditory stimulation as a function of the alert signal.

However, the triggering of an alert signal at each crossing of a threshold value of alert acceleration results in numerous untimely triggerings. Indeed, strong acceleration can be caused not only by kinetic engagement, but also by other factors, for example when the foot hits an obstacle.

Thus, preferably, the calculation means are configured to command the transmission means to emit an auditory stimulation from the moment when at least two warning signals are generated in a time interval of less than 0.5 second, preferably less than 0.3 seconds. Therefore, an isolated overshoot of the alert acceleration threshold value does not result in the generation of auditory stimulation.

However, even with the requirement of the temporal proximity of two threshold crossings, there may be false alarms resulting in unwanted triggering of auditory stimulation. The detection of a frequency close to the steps is therefore used. To do this, the storage means store a time threshold value and a walking acceleration threshold value, and the calculation means are configured to measure a time interval between two measurements of acceleration exceeding said acceleration threshold value. speed and trigger an alert when an interval of time between two consecutive exceedances of said walking acceleration threshold value is less than the stored time threshold value.

The walking acceleration threshold value is less than the warning acceleration threshold value. For example, it is lower, in absolute value, than 3m.s ^-2 . The amplitude overshoot of the walking acceleration threshold value by the measured accelerations corresponds to the detection of a step. The time interval between two consecutive overshoots therefore corresponds to the time interval between two steps. During an episode of kinetic clutch, the time interval between steps decreases. A second criterion relating to the frequency of steps is therefore added to the first criterion for exceeding the alert acceleration threshold. This makes it possible to better detect the episodes which really correspond to a kinetic clutch.

Furthermore, strong accelerations can be detected in the absence of kinetic clutch, in particular when the person changes position, for example when climbing a staircase. In this case, it is advisable to detect this situation which does not correspond to walking. For this purpose, the accelerometer is suitable for measuring an acceleration in another direction different from the second direction, and preferably perpendicular to the latter; and the storage means memorize a second threshold acceleration value. The calculation means can then be configured to inhibit the generating an alert signal for a predetermined duration when an acceleration measured at a value greater than this second alert acceleration threshold value.

More generally, the calculation means are configured to detect from the measurements of the accelerometer, and / or possibly by those of a gyrometer or gyroscope, the position of the body and the displacement or rest situation of the person wearing said. accelerometer. The position of the body can be determined by means of the detection of the acceleration of the earth's gravity, which indicates the vertical, or else directly by the gyroscope. The storage means memorize a threshold value for walking acceleration, and the calculation means detect a rest position of the person wearing the accelerometers when all the values measured by the accelerometers are below the threshold value for walking for a period greater than a predetermined time.

Thus, when the person is detected to be standing, he is considered to be at rest when only accelerations included in an acceleration interval, such as -1 ms ^-2 and 2.8 ms ^-2 in the vertical direction, for a time interval such as 2.5 s. When the person is detected as sitting or lying down, he is considered to be at rest when only accelerations included in an acceleration interval are measured, such as between -1.5 ms ^-2 and 1.5 ms ^-2 in the vertical direction, for a time interval such as 0.35 s.

• une première période de mesure lorsque le tronc de la personne est non-vertical, c'est-à-dire lorsqu'elle est couchée ; et/ou
• une deuxième période de mesure inférieure à la première valeur, lorsque le tronc de la personne est vertical, c'est-à-dire lorsqu'elle est assise ; et
• une troisième période de mesure inférieure à la deuxième valeur, lorsque la personne marche.

The calculation means are configured to compare the accelerations measured by the accelerometer periodically, the value of this period being equal to:

• a first measurement period when the person's trunk is non-vertical, that is to say when he is lying down; and or
• a second measurement period less than the first value, when the person's trunk is vertical, that is to say when he is seated; and
• a third measurement period less than the second value, when the person is walking.

For example, the first measurement period is greater than 75 ms, and is for example 100 ms, while the second measurement period is between 75 ms and 25 ms, and is for example 50 ms, and the third period measurement is less than 25 ms, and is for example 10 ms.

The auditory stimulation emitted upon detecting the occurrence of a kinetic engagement episode is preferably the same as in preventing the kinetic engagement, and the period of the pulse of the auditory stimulation is based on a period of. reference stored in the storage means, linked to the time value used to detect an excessively rapid frequency of steps. The period of the pulsation is calculated based on the average period of steps when the person walks without exhibiting kinetic clutch.

The auditory stimulation can be emitted upon detection of the kinetic clutch, using the warning signals described above, or be emitted at the expiration of a delay which follows the detection of the kinetic clutch. This time delay can be from 0.1 to 37 seconds for example, but, when it is present, it can be at least 2 seconds, for example 10 seconds. Prior to the time delay, a stop signal is emitted by the transmission means, indicating to the person to stop. This makes it possible to bring the person back to a motor function that he / she controls, that is to say immobility, then to make it start again thanks to the auditory stimulation following the delay.

However, stopping the person can lead to falls, as they may become unbalanced during kinetic engagement. Moreover, the duration of the delay slows down the movements of the person accordingly. Thus, the auditory stimulation is preferably sent without delay, or with a very low delay, less than a tenth of a second.

In addition, it is common during a kinetic clutch that the heart rate of the person increases, and suddenly becomes higher than a normal walking heart rate of that person. This higher heart rate can be used to distinguish a kinetic clutch among other cases that could potentially lead to similar accelerations. To this end, the device may comprise means for measuring the heart rate suitable for being worn by the person in order to measure his heart rate. The storage means then memorize a heart rate threshold value and the calculation means are configured to generate an alert signal when the measured heart rate has a value greater than the stored heart rate threshold value, the latter corresponding to a normal walking heart rate of this person, previously determined.

The figure 2 illustrates the accelerations measured in the vertical direction for a person with Parkinson's disease when walking and experiencing kinetic clutch.

In a first part 20, the person walks without exhibiting any kinetic clutch. The measured accelerations are below the alert acceleration threshold represented by the horizontal dashed lines, at the top for positive values and at the bottom for negative values. In addition, the acceleration peaks which exceed the walking acceleration threshold value are spaced apart by a time interval greater than the time threshold value.

A calibration of the assistance device is implemented to adapt to the person wearing the device the various values used in the context of the use of the device, such as the threshold value of alert acceleration.

In a second part 21, a kinetic engagement occurs. The amplitudes of the accelerations are greater, and exceed the alert acceleration threshold value. In addition, the acceleration peaks which exceed the walking acceleration threshold value approach each other: the time intervals separating them are less than the time threshold value.

The first two exceedances 24, 25 of the alert acceleration threshold value occur within a time interval of less than a few tenths of a second. The calculation means then command the transmission means to emit the auditory stimulation after a time delay of 10 seconds. During this time delay of 10 seconds, the person undergoing the kinetic clutch is at a standstill, which corresponds to the near-zero acceleration values of part 22. A stop sound may be emitted to indicate to the person to s' stop, which prevents him from falling. It is also possible to emit the auditory stimulation as soon as the kinetic engagement is detected, without delay.

Here, the audible signal is emitted from 30 ^th second. The fourth part 23 thus corresponds to the resumption of walking by the person hearing the auditory stimulation. It can be seen that the acceleration peaks are regularly spaced with regular amplitudes, thus indicating the resumption of regular and harmonious walking.

In the context of this calibration method, the accelerometer is placed on the person, in particular at the level of his belt, that is to say at the level of the iliac crest, as illustrated on the figure. figure 1 . As before, the accelerometer can be placed at the level of the trunk, hips, plexus, or lower limbs. The person then walks, and at least one series of acceleration measurements is acquired while the person is walking, using the accelerometer.

These acceleration measurements are used to determine the parameters (amplitude of accelerations, pace, etc.) of a person's normal walking, that is to say in the absence of an episode of kinetic clutch. To this end, the series of acceleration measurements is cut off from the parts corresponding to an impaired motor skills of the person, that is to say to the parts corresponding to episodes of kinetic clutch, and more generally to non-normal walking. . This selection from the series of acceleration measurements can be made manually by a professional who observes the patient's gait, since an episode of kinetic clutch is clearly identifiable by a professional. The selection can also be based on the observation of measurements, since, as on the figure 2 , the parts corresponding to a normal operation and the parts corresponding to a kinetic engagement or to a stop are easily identifiable.

Then, from the series thus amputated, it is possible to determine the parameters of a normal walk. In particular, a calculation on the data of the accelerations makes it possible to determine the alert acceleration threshold beyond which the measured acceleration is considered to be abnormal and which may indicate the occurrence of a kinetic clutch. The calculation on the data of the accelerations to determine the alert acceleration threshold can for example involve statistical concepts such as the average of the amplitudes of the accelerations and their standard deviation.

The alert acceleration threshold can be scalable, with a first determination by means of a first series of samples extracted from the amputated series, then a confirmation or modification of this threshold by means of other series of samples. , extracts from the same amputated series or from another amputated series from the same person.

The walking acceleration threshold value can also be determined from the average of the accelerations. The time threshold value can also be determined from the amputated series, by detecting the acceleration peaks corresponding to a step and thereby determining the pace of the walk.

Furthermore, when walking during which the series of accelerations is recorded, the person preferably wears a heart rate monitor, and his heart rate is measured at the same time as the acceleration. This heart rate can be used to keep only the parts of the series corresponding to a normal walk: the parts associated with a heart rate higher than the average during his walk are discarded.

Indeed, these parts can indicate not only the occurrence of a kinetic clutch, but also other stressful events which could result in an abnormal gait.

Moreover, whether it is for the implementation of the calibration method or for monitoring the person wearing the device during its use, the calculation means are preferably configured to store, on the storage means, the measurements taken. by at least by at least one measuring device of the assistance device, such as the accelerometer and / or the heart rate monitor. It is then possible to carry out periodic recalibrations of the device on the basis of the measurements taken by the latter during the use of the device, and stored in the storage means. It is thus possible to provide for a recalibration period of between several times a day and once a week.

The invention is not limited to the embodiment described and shown in the appended figures. Modifications remain possible, in particular from the point of view of the constitution of the various elements, without thereby departing from the field of protection of the invention defined by the appended claims.

Claims (15)

1. An assistance device for a person (1) suffering from motor disorders of neurological origin likely to cause freezing of gait, comprising:

   • an accelerometer adapted to be worn by the person (1) to measure accelerations along at least one first direction which corresponds to the horizontal axis; and

   • means (5) for emitting an auditory stimulation perceptible by the person wearing the accelerometer; and

   • calculation means connected to the accelerometer, to storage means and to the emission means;

   the storage means storing a plurality of anticipatory acceleration threshold values previously defined for said first direction, each anticipatory acceleration threshold value being associated with a posture, and the calculation means being configured to:

   a) determine a posture of the person from the measured accelerations,

   b) compare the accelerations measured by said accelerometer in the first direction relative to at least one anticipatory acceleration threshold value associated with said posture;

   c) control emission of an auditory stimulation based on said anticipatory acceleration threshold value associated with said posture being crossed;

   the assistance device being characterised in that the calculation means are configured to:

   - also associate each posture with a determined period of time being a function of the crossing sense of said anticipatory acceleration threshold value by the measured accelerations, and

   - control emission of the auditory stimulation based on said anticipatory acceleration threshold value associated with said posture being crossed during the determined period of time.
2. The device according to the preceding claim, wherein the posture is a seated-lying posture, and an anticipatory acceleration threshold value associated with the seated-lying posture corresponds to a backward loss of balance, the calculation means being configured to control emission of the auditory stimulation when the measured accelerations are greater than said anticipatory acceleration threshold value associated with the seated-lying posture corresponding to a backward loss of balance.
3. The device according to one of the preceding claims, wherein the posture is a standing posture, an anticipatory acceleration threshold value associated with the standing posture corresponding to a backward loss of balance and an anticipatory acceleration threshold value associated with the standing posture corresponding to a forward movement, the calculation means being configured to control emission of the auditory stimulation when the measured accelerations are lower than the anticipatory acceleration threshold value associated with the standing posture corresponding to a backward loss of balance and when the measured accelerations are greater than the anticipatory acceleration threshold value associated with the standing posture corresponding to a forward movement.
4. The device according to one of the preceding claims, comprising an inertial unit of which the accelerometer is part, said inertial unit being adapted to be worn on the person's trunk and being further configured to determine an orientation of the person's trunk, said orientation being used to determine the person's posture.
5. The assistance device according to one of the preceding claims, wherein the calculation means are configured to control emission means to emit the auditory stimulation according to a reference period corresponding to a calculated frequency of the person's steps.
6. The device according to one of the preceding claims, wherein the accelerometer is also adapted to measure accelerations along a second direction, said second direction corresponding to the vertical, and the storage means store at least one alert acceleration threshold value previously defined in a second direction, the calculation means being further configured to

   a) compare the accelerations measured in the second direction relative to said at least one alert acceleration threshold value,

   b) generate an alert signal when a measured acceleration has a value greater than the alert acceleration threshold value;

   c) control emission means to emit an auditory stimulation based on the alert signal.
7. The device according to the preceding claim, characterised in that the storage means store a time threshold value and a walking acceleration threshold value, and in that the calculation means are configured to measure a time interval between two acceleration measurements exceeding said walking acceleration threshold value and trigger an alert when a time interval between two consecutive exceedances of said walking acceleration threshold value is lower than the time threshold value stored.
8. The assistance device according to one of claims 6 to 7, wherein the storage means store a reference period corresponding to the time threshold value, and the calculation means are configured to control emission means to emit the auditory stimulation according to the reference period.
9. The assistance device according to one of claims 6 to 7, characterised in that the calculation means are configured to control emission means to emit an auditory stimulation from the time when at least two alert signals are generated in a time interval lower than 0.5 second, preferably lower than 0.3 second.
10. The assistance device according to one of the preceding claims, characterised in that it comprises:

    - means for measuring the heart rhythm adapted to be worn by the person to measure the heart rhythm thereof; and in that

    - the storage means store a heart rhythm threshold value;

    and in that the calculation means are configured to generate an alert signal when the measured heart rhythm has a value greater than a heart rhythm threshold value stored.
11. The assistance device according to one of the depending claims, wherein the accelerometer is configured to measure an acceleration along another direction different from that of the second direction, and the storage means store a second alert acceleration threshold value associated with said other direction, and the calculation means are configured to inhibit the generation of an alert signal during a predetermined period of time when an acceleration measured in said other direction has a value greater than the second acceleration threshold value stored.
12. The assistance device according to the preceding claims, wherein the storage means store a walking acceleration threshold value and a rest time value, and the calculation means are configured to detect a seated or lying position of the person wearing the accelerometer when all the acceleration values measured by the accelerometer are lower than the walking acceleration threshold value during a period of time greater than the rest time value.
13. The assistance device according to one of both preceding claims, characterised in that the calculation means are configured to compare the accelerations measured by the accelerometers periodically, the value of this period being equal to:

    - a first measurement period when the person's trunk is non-vertical; and/or

    - a second measurement period lower than the first value, when the person's trunk is vertical; and

    - a third measurement period lower than the second value, when the person is walking.
14. A method for calibrating an assistance device according to one of the preceding claims, comprising steps in which:

    - the accelerometer is disposed on the person's trunk,

    - a series of acceleration measurements is acquired while the person is walking,

    - the series is truncated of parts of the series of acceleration measurements corresponding to an impaired motricity of the person,

    - the anticipatory acceleration threshold values and/or the alert acceleration threshold value are determined from the accelerations of the truncated series.
15. The calibration method according to the preceding claim, wherein the walking acceleration threshold value and/or the time threshold value are determined from the average of the accelerations of the truncated series.

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